armody

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Hi there all,

From time to time I came up with different topics and different questions. As I have quite a stock of those questions therefore from time to time I come up with those and get benefitted from all you senior people's experiences.

My questions is when any 2 Stroke engine or 4 Stroke engine requires to be disassembled taken out everything then put everything back together and start using again. One thing I understand is cleaning, take the gunk out of it, or some kinda other impurities/pebbles which may get into the engine while flying or taxiing on the ground or grass.

Second thing I have been flying for more than 1 and half year and I can fit servos, install engine, tank etc, I mean I can make an ARF ready or RTF but would need some time to make a kit. I have never disassemble any engine. I would like to disassemble the engine and I wanna see inside, clean it and then assemble it back again. Is it easy to do that or not, if a person like me has never done it before, does he require to have a guidance of a senior or can do it on his own in order to learn and get hand on experience. As it is said, one can never know the depth of water until he/she steps into it.

Please guide and have your feed back

Thanks in advance

Mody

armody

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Sorry Addition to my first question

Why disassembling gets necessary of any 2C or 4C engine, except when it needs to be completely cleaned? and what are the chances of it being damaged after being disassembled by a non experienced person, and does disassembling really important for any engine which gives you such a hard time and then it can be re-assembled and starts performing well?

Thanks

Mody

piper_chuck

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I'm curious about this question, so I'll ask you a question. Why do you feel it needs to be cleaned inside? Is it no longer performing up to standards? There's an old saying, if it ain't broke, don't fix it. How often do you hear of people tearing down their car (full sized) engines, just to clean 'em up?
Some people are quite good at all things mechanical and even when disassembling something new, seem to do good at putting them back together. Other people would be better off sending their engine to someone who knows what they are doing.
Are you having trouble with your engine? Is that perhaps the reason you want to disassemble it? There's little that can be happening inside an engine that could be repaired by merely disassembling, cleaning, and reassembling, unless perhaps it's all gummed up due to being left with old fuel inside. Even then, much of that can be resolved by just removing the carb and back plate. If something is wrong inside the engine, it's probably only going to be fixed by replacing parts such as bearings, piston/liner, etc.

I almost never disassemble my airplane engines. I guess I'm from the old school. If the bearings feel good and the compression is still strong, I see little reason to open up the engine and mess with it. I do regularly disassemble my boat engines, perhaps every or every other season, but that's because I push them so much harder than airplane engines.

If you're curious about what's inside your engine, removing the back plate is relatively safe. If it's got a gasket, be sure not to tear it. This will let you see the lower part of the liner, the connecting rod, back of the crankshaft, and get a glimpse at the main bearing. Removing the carb is also relatively safe, but all you'll be able to see is part of the crankshaft. I personally do not remove the head unless I suspect there is something wrong with the piston or liner.

Montague

I agree with Chuck, if the engine runs fine, don't take it apart.

Depending on the brand of engine, there are lots of things you can do wrong when putting it back together to make it not run right, or possibly even fail in flight.

If the engine isn't running right, usually the problem is something to do with the fuel system or the carb, something like leaking air. After that, you might have a leaking backplate or head (backplate is more common).

However, ther are times when taking apart an engine is the way to fix it. Just last night, one of my student's engines was really stiff and "draggy" when rotated by hand through BDC (bottom dead center). Something inside the engine is binding, and that's causing wear and robbing power. It's time to take that engine apart to find out what's wrong.

I've also had engines get full of dirt in a crash, I've even seen dirt all the way on top of the piston after hitting soft mud, straight down, at full throttle. Amazing, really. That takes a full "take it apart and clean all the dirt out" approach.

But usually whe you hit the dirt, taking the carb and backplate and head off are enough. Look for dirt in the carb, under the carb, inside the crankshaft, around the crankshaft, inside the case, then inside the combustion chamber in that order. That's how stuff "travels". For example, if you find dirt in the carb, but not in the crankshaft or behind the backplate, then it couldn't have gotten in to the ports or combustion chamber. So you clean the carb and leave the rest alone.

On some engines, if you hit something hard enough, you can pop the cranshafts back and they will rub the backplate. My Webra .25s that I fly in combat do this on a fairly regular basis. When it happens, you have to take the engine apart enough to pop the crankshaft out and re-seat it. It's a hassle, but doable pretty quickly since you don't have to mess with the bearings.

If you run an engine hot enough, long enough, you can sometimes build up a carbon varnish on the top of the piston. If you build up enough of this, you raise the compression ratio of the engine, and the carbon holds heat better than the metal, the result can be an engine that backfires and pre-detonates and won't run well at all. In that case, taking the piston out and cleaning the carbon off the top (and sometimes the carbon off the combution chamber part of the head as well) will help. But on some engines a little varnish can actually help improve compression, and I know more than one guy who cleaned all the compression right out of his engine. Not a good thing. It's espeically easy to "clean" the fit between piston and liner and ruin the compression fit.

I forgot, a common reason to tear down an engine is to replace bearings due to rust. If an engine feel "crunchy" and doesn't feel nice and smooth as you turn it, then you might have bearing problems, and that's a good reason to take an engine apart. Sometimes though, a little congealed oil (espeically caster) will give an engine that feel, but filling it full of a good light oil will losen that up and the engine smooths out.

So, like Chuck said, if it's not broke, don't "fix" it.

opjose

To add to Montague's post...

If you ever do have an engine full of mud, take off the carb and glow plug, and flush the engine with that half gallon of glow fuel left over from last season.

Use a sprayer and paint brush to get at the outer surfaces and flush, flush, flush until all of the debris is gone.

I've even resorted to first flushing the engine out with water ( which is better to desolve the mud and debris ) then immediately follow that with copious amounts of old glow fuel to get rid of the water, etc.

Then I slowly rotate the crankshaft trying to feel any resistance from "grit".

If everything turns smoothly, it gets yet another flush and is put back together.

I haven't had a problem with this...

Montague

I actually use carb cleaner from an autoparts store for blowing dirt and stuff out of motors. Old fuel does work in a pinch, but I worry about leaving "cold" fuel in an engine, it seems to promote rust. The carb cleaner will wash away oil as well, so when I do that, I follow it up with a heavy dose (not drops, big squirts) of oil. I prefer automatic transmission fluid for this, as it penetrates and is good at getting rid of dirt and water.

I also pop the head, backplate, and muffler off so I can see if there is grit in there and get a clearer shot. For example, if there is dirt inside the crank, and you just shoot in through the carb, but don't pull the backplate, you just forced more dirt down deeper in to the engine. So pulling the backplate allows everything to come out before it reaching the piston/liner area.

If you don't pop the head, at least get the backplate and muffler and glowplug and have a good look.

opjose

Yeah...

Popping the head can be problematic for a newbie, in terms of getting everything back in place with an overhaul kit...

However pulling the backplate as you've mentioned is also very easy to do and will help flush out any debris.

armody

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Piper Chuck, Montague, Ophose,

Thanks for your very fruitful replies. I never had engine problem, until I had this engine HB .61 which is not PDP, that engine gave me such hard time, my friend senior flyer even gave up on it, so he gave me K&B's old engine which is also .61 and a fuel pump at the rear right after back plate. I don't use that fuel pump. HB engine is the one I wanna disassemble it and see what exactly the problem is and then I would probably drop car engine oil into it in order to get rid of grits sands etc. I have seen an engine how it looks from inside, and how piston moves up and down, and turns the crankshaft. I also had Evolution's .45 engine came with P51 Mustang PTS, it flew my plane good for more than a year, after that engine started gave me trouble and as I dont have any 40 size plane mustang crashed[&o] so point of using it. I also wanted to open it too why it started giving me hard time.

Now as far as K&B engine is concerned that is my friend's engine, and naturally he gave it to me to use it and as Im entrusted to that engine, I cannot disassemble it, I can only do it to my engine, which I left it at my friend's house which I can get it anytime. Thatswhy I wanted to disassemble my HB german engine to look into it and unearth what really is the problem. For the last 6 years I have been in severe financial crisis, but I have not given up my hobby, now condition is this that I cannot buy a new engine of $100 which I prefer ASP or Magnum. But I have offers from bank and from an insurance company prolly I'd join insurance company as they are expected to pay more. Anyway, thats not the topic, infact Im desperately waiting for my immigrant visa which has been stuck under the security check for the last 8 months and this 18th its gonna be 9 months. I wanna continue my hobby in USA, I wanna do a good job in general insurance company, do my MBA and another Master as this is a beautiful hobby, and I would continue doing it and ofcourse USA is the LAND OF OPPORTUNITIES and have more stuff of RC available than Pakistan. Anyway, I'd take your advices, I won't disassemble the engine, but I would certainly give it to my friend who had been doin this job pretty well.

Thanks again for your input

Happy Flying [8D]

Mody

armody

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sorry for your name's spellling but i think pronunciation is correct, opjose

Jim Thomerson

When you take an engine apart, have a clean plce to put all the parts. Don't lose any parts. Be gentle and don't force anything. Pay attention to how things were oriented, and put them back the same way. Oil it up good when putting it back together.

E-Mo

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This is some good reading check it out

http://www.airfieldmodels.com/inform...s/starting.htm

Link to engine disassembly

http://www.airfieldmodels.com/inform..._an_engine.htm

Montague

If the engine ran fine, but now suddently doesn't, and by not running fine, you mean it seems hard to set the mixture, the engine is always running lean or rich, then it's probably a problem in the carb. Often it's just a bit of dirt or something inside the needle valve or spraybar, and if you just remove the carb, then remove the needle and run fuel through everything, you might wash out the problem.

armody

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Thanks a lot Jim, E-Mo, Montague,

Yes Carburetors did give me hard time, nearly 3 to 4 carbs have been changed, but no positive outcome, anyway, I think Im gonna disassemble it or get it done by my friend, but I'd probably do this is how I'd learn. Thanks for your advices and E-Mo great site about engine disassembling. I'd prolly do it next week and keep you posted about it.

Thanks again

Mody

Montague

Btw, do you use a fuel filter in between the tank and the carb? If not, do you use a filter in between the fuel jung and tank when you fuel the airplane? Do you keep your fuel gallon sealed and work to keep dirt out of the lines espeically the end of the line when you're plugging and unplugging it from the model to fuel? I've seen (and done myself) situations where there's a lot of solid junk (dirt, plastic bits, etc) in the fuel that keeps finding it's way in to the carb and blocking the needle and/or spray bar. It can be really hard to figure out what's going on, since you clean it out, it seems to run better for a moment, then clogs back up. Also, if you are using a filter on the plane, try back-flushing it, it could be blocked. I've had that happen as well. (showed me how well the filter was working as well...)

Warbird Joe

After my mid-air my engine was completey under ground in the mud. I got it home and took off the carb and the glow plug. I didn't need to take the muffler because it was sheared off at the muffler extention. Anyway, I soaked the engine in water to get the dried dirt wet again. After it was wet I sprayed it out with the hose. I turned the crank slow to feel for risistance and sprayed more until all the dirt was out. After that I blew out the water with an air compressor. Then put after run in the engine and turned it a few more times with my starter. Filled up the gas tank and started the plane. It never skipped a beat and it is still running great. Just my 2 cents worth

bruce88123

On your K&B engine with the pump. If it still has the original pump carb that came with the pumped engine it is larger (venturi) than a non-pumped engine. You simply can NOT get full power from this engine without using the pump. Also without the pump it won't run right, because of the large venturi it doesn't have as much vacuum to draw fuel properly. You need to either hook up the pump or use a standard venturi size carb. I've owned many of these over the years and am very familiar with them. Got one flying right now in an Extra 300 and another brand new one waiting for a plane.

armody

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Thanks Montague, Bruce, hdwideglide for your fruitful replies. Yesterday which was sunday, I took the plane to the flying field afer 15 days, as we missed one sunday. I started the plane, tuned it, gave great rpms, took a flight, infact, it flew nearly 5 to 7 minutes with K&B engine then dead stick, as we were flying on somebody's land either occupied land or bought land, we were told to move, as armed guards came to us and requested sir, we have order to ask you to leave and not to fly our planes, anyway, we moved, how people can be so stupid and ignorant, its pretty hard for somebody to comprehend. Anway, I don't use fuel filter, second thing, we do have much contact of dirt and dirt does get into the fuel pump pipe but we clean it from time to time, never had any problem with my ASP .46 engine, anyway yesterday we had to move to some other plane where its a big open land on acres, and roads are all around, so my plane had a dead stick not much after the take off, as there was no wind at all, took a wild nose dive, it tried my best to save it from being crashed, but it hit the road and broke all landing gears and split in 2 from front right behind the fuel tank. Anway, Im waiting to get my sports plane, a little faster probably something like Venus of GP and with new engine, hopefully in a month I'd get it and it would be my 3rd plane level wise. I'd take care of fuel, and be more careful about dust particles, and bruce, Im gonna give this K&B pump engine back to my friend, and I'd buy new .61 Magnum or ASP engine or probably Thunder Tiger.

Thanks for you input all

Mody